The objective of this study was to establish the predictability of a pharmacokinetic dosing method (adapted to accommodate a TI 59 Programmable Calculator) to establish amikacin dosages based on lean body weight, estimated creatinine clearance, a standard amikacin elimination rate constant and desired peak (25 mcg/m1) and trough (5-8 mcg/m1) concentrations. Steady state serum peak and trough concentrations were measured by a radioimmune assay technique. The measured levels were then used to calculate the patient specific elimination rate constant and volume of distribution. If necessary the maintenance dose was adjusted using these values. One hundred sixty-three consecutive granulocytopenic patients participating in an empiric antibiotic trial had amikacin dosages calculated in this manner. One hundred twelve evaluable trials were completed using this initial dosing method. The median peak concentration was 20.4 mcg/m1 and the median trough concentration was 6.25 mcg/m1 using this method. One hundred fifteen dosage adjustments were made using the second method. The median peak concentration was 25.3 mcg/m1 and the median trough concentration was 8.1 mcg/m1 using the adjustment method described above.